Although second harmonic (sh) imaging is widely available in most contemporary ultrasound systems, its accuracy to evaluate left atrial appendage (LAA) morphology and function remains poorly characterized. We conducted a cross-sectional survey of patients with acute ischemic neurologic conditions (n = 51) who underwent both transesophageal and transthoracic echocardiography (TTE) to explore the performance of sh in LAA assessment. Doppler and LAA area evaluation by sh TTE were feasible in most patients (98%). We observed positive and significant associations between sh TTE and transesophageal echocardiography assessment of LAA peak emptying velocities (r = 0.63, P < .001) and LAA maximum area (r = 0.73, P < .001). In addition, all patients (n = 7) with LAA thrombus or spontaneous contrast had peak emptying velocities less than 50 cm/s on sh TTE (negative predictive value of 100%). In multivariate analysis, LAA peak emptying velocity remained independently associated with LAA thrombus or contrast. In conclusion, sh TTE can provide valuable and clinically relevant information of LAA morphology and dynamics.